mirror of https://github.com/saitohirga/WSJT-X.git
24 lines
481 B
Fortran
24 lines
481 B
Fortran
subroutine degrade_snr(d2,npts,db,bw)
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integer*2 d2(npts)
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real dat(60*12000)
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dat(1:npts)=d2
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p0=dot_product(dat(1:npts),dat(1:npts))/npts
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if(bw.gt.0.0) p0=p0*6000.0/bw
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s=sqrt(p0*(10.0**(0.1*db) - 1.0))
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do i=1,npts
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d2(i)=nint(dat(i) + s*gran())
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enddo
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! dat(1:npts)=d2
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! p1=dot_product(dat(1:npts),dat(1:npts))/npts
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! if(bw.gt.0.0) p1=p1*6000.0/bw
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! write(*,3001) db,bw,p0,s,10.0*log10(p1/p0)
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!3001 format(5f10.3)
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return
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end subroutine degrade_snr
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